Seed Set and Germination of Eldarica Pine 1 Influenced by Cone Hierarchy John T. Harrington, John G. Mexal, and James T. Fisher2 Harrington, John T.; Mexal, John G.; Fisher, James T. 1989. Seed Set and Germination of Eldarica Pine Influenced by Cone Hierarchy. In: Landis, T.D., technical coordinator. Proceedings, Intermountain Forest Nursery Association; 1989 August 14-18; Bismarck, ND. General Technical Report RM-184. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station: 65-69. Available at: http:www.fcnanet.org/proceedings/1989/harrington.pdf Abstract.-- Tree and cone hierarchy effects on eldarica pine seed quantity and quality are examined. Hierarchy, or location of cone whorl on a branch, and tree significantly influenced total number of seed/cone, number of viable seed/cone and percent viable seed. Whorl 2 cones, the distal whorl, had 54% more seed/cone and a 65% greater percent viable seed. Percent germination, total germination, G50 and number of cones/whorl were not effected by either tree or hierarchy. Relationships between total number of seed/cone and number of seed germinating/cone and percent germination are provided. Potential causes for hierarchal effects are discussed. INTRODUCTION Eldarica pine ( Pinus eldarica Medw. ( = P. brutia subsp. eldarica) ) is a member of the Pinus brutia group of mediterranean pines (Spencer 1985). The only naturally regenerating population of eldarica pine occurs from 200 - 600 meters elevation in the semi-arid steppe region in the Russian republic of Georgia (Zimina 1978, Mirov 1967 as cited by Spencer 1985). This species, however, has been introduced to numerous countries in Europe, the middle east and Asia, as well as the United States and Australia (Fisher 1985). Eldarica pine was first introduced to the United States in 1961 in southern California (Spencer 1985). Figure 1.--Potential distribution of eldarica pine in the Eldarica pine is used for Christmas and ornamental United States (Fisher 1985). trees, and in windbreaks throughout its potential range (fig. 1). Eldarica pine can tolerate alkaline soils (Fisher 1985), high levels of salinity (Manuchia 1986) and demonstrates growth rates comparable to Pinus radiata wood properties of eldarica pine indicate it has potential and Pinus caribaea when well watered (Fisher et al. for manufactured wood, paper pulp and fuelwood 1986). Eldarica pine's polycyclic growth habit and deep root system allow it to fully utilize the long growing production (Fisher 1985). seasons and deep soil moisture reserves found in regions of the southwestern United States. Furthermore, tests on Russia, Iran, Afghanistan and Pakistan are the leading growers of eldarica pine worldwide. Because of the international relations with these countries and the lack of a worldwide seed certification program for eldarica pine, 1 obtaining seed can be time consuming, difficult and Paper presented at the Intermountain Forest Nursery expensive. While seed companies in the United States Association Annual Meeting (Bismarck, ND, August 14-17, sell eldarica pine seed, seed costs and quality vary 1989). New Mexico Agric. Exp. Sta. Scientific Paper no. dramatically. Costs incurred by local (Las Cruces, NM) 338 nurserymen in 1989 ranged from $110 to $310 per kilogram ($50 to 140/lb) and seed germination varied 2 Ph.D. candidate, Professor, Professor Dept. of Agronomy and Horticulture, New Mexico State University, Las from 30 to 60% following float sorting of the seed. Cruces, NM 88003. Figure 2.—Photograph of 4 cone whorls produced on an 17 year- old eldarica pine branch growing in Las Cruces, New Mexico. Eldarica pine has a relatively unique cone production seed (pops). Total seed number does not include habit, similar to Pinus clausa and Pinus caribaea (USDA first-year aborted ovules (seedless wings) that were 1974). Individuals can set multiple flushes or whorls of observed but not counted. These terms are described in female cones during one growing season (fig. 2); however, detail by Bran-Jett et al. (1977) and are addressed in the this response is site specific (USDA 1974). This trait affords discussion section of this report. eldarica pine growers in this region the ability to produce large quantities of seed in a short time (relative to single whorl species). The purpose(s) of this study was to determine if cone heirarchy influenced seed quantity and Germination quality in trees demonstrating this multi-whorl habit, and to examine the tree-to-tree variation in this response. Eldarica pine has no reported stratification requirement so none were performed. Following extraction, seeds were soaked for 10 hours in distilled METHODS AND MATERIALS water (25°C). The soaking served two purposes, it separated filled (sinkers) from unfilled (floaters or pops) seed, and allowed the seed to soak up enough water to initiate the germination process. The floaters were Plant Material air-dried for 48 hours, and their weight and numbers were recorded. These seed were subsequently examined for Three, 10-year old plantation-grown eldarica pine filling and relatively few (ca 0.7%) were filled. trees at the Fabian Garcia Science Center in Las Cruces, NM were randomly selected and used in this study. The two Filled seed was hand sown in flats of steam most recently matured cone whorls were harvested on two branches of each tree on November 2, 1988. The two sterilized vermiculite, and covered with clear plastic to maintain a moist environment. Flats were placed on lab whorls of cones per branch were labeled. Whorl I was the benches where temperatures ranged from 21 to 25°C. first whorl of cones produced on the branch; therefore, the Germination was monitored for the next 30 days. A seed whorl closest to the bole of the tree. Whorl 2 was the was considered germinated when the hypocotyl broke the second whorl of cones produced on the branch during the growing season, and was the whorl closest to the periphery vermiculite surface. Percent germination, total germination and G , or date at which 50% of the seed of the crown. No information was taken on the difference in 50 germinated, were determined from this information. time between cone whorl production. Eldarica pine has serotinous cones, so seed was extracted by hand using a grafting knife to peel back the cone scales and expose the seed. Total number of seed Statistical Considerations and total seed weight were recorded following extraction. Total number of seed includes all developed seed and large second year aborted ovules (i.e. pops). According to The experimental design was a randomized Bramlett et al. (1977), developed seed can fall into three complete block design with blocking by tree and branches catagories: filled, partially filled and empty serving as repetitions per block. Table 1 Table 1.--Analysis of variance partitioning of degrees of Table 2.-- Mean cone and seed attributes and observed freedom for the study design. significance levels ( PR>F ) for the three plantation-grown eldarica pine. Seed Wt. (mg) = mean weight of sound seed; ‘-‘ = tree 1 material failed to SOURCE df reach 50% germination Tree (Block) 2 Whorl 1 Tree Interaction 2 Parameter 1 2 3 PR>F Exper Error 7 Cones/whorl (no.) 3.8 3.3 2.8 0.488 Total Seed/Cone (no.) 54 103 62 0.004 Total 11 Sound seed/cone (no.) 28.2 11.1 27.5 0.003 Sound Seed (%) 41.7 68.8 38.2 0.050 illustrates the partitioning of the degrees of freedom of the Seed Wt (mg) 70.7 56.9 61.7 0.116 design. Analysis of variance was performed to test the effects of source (tree) and whorl position on cone number Germination (%) 24.4 79.8 64.0 0.004 per whorl, total number of seed per cone, total number of G50 (d) - 12.9 21.3 0.262 viable seed per cone, percent viable seed, mean weight of viable seed, total germination, percent germination and G50. Analysis was performed using the PROC GLM of SAS- Table 3.--Mean cone and seed attributes and observed Version 5 (SAS Institute Inc. 1989). significance levels ( PR > F ) for whorl 1 and whorl 2 of eldarica pine. Seed Wt. (mg) = mean weight of Regression analysis was performed using number of sound seed sound seed per cone as an independent variable on the dependent variables, number of seed germinating per cone Whorl and percent germination. Analysis was performed using the PROC REG of SAS Version 5 (SAS Institute Inc., 1989). Parameter 1 2 PR>R Cones/whorl (no.) 3.2 3.3 0.804 Total Seed/cone (no.) 57 88 0.008 RESULTS Sound Seed/cone (no.) 26.6 58.0 0.004 Sound Seed (%) 38.9 64.1 0.019 Tree significantly impacted both seed quality and Seed Wt. (mg) 64.6 61.6 0.546 quantity (table 2). Among individual trees, tree 2 had both Germination (%) 51.1 60.8 0.333 the greatest number of seed per cone, number of viable G (d) 19.5 14.7 0.503 seed per cone as well as the greatest percent viable s eed. 50 Tree 2 also had the highest percentage germination. While not statistically significant (alpha = 0.05), source appeared The relationship between germination percent and total to influence mean weight of viable seed and G (PR > F = 50 number of extracted seed per cone is also positive and linear 0.116). Trees 1 and 3 had comparable numbers of viable seed per cone but total number of seed per cone and (fig. 4). However, this relationship is weaker as indicated by the lower correlation coefficient and the wider confidence limits. percent viable seed differed. Cone heirarchy or whorl position also impacted seed quantity and quality attributes. Whorl 2 cones, those closest to the periphery of the crown and latest to develop, had DISCUSSION significantly greater total seed, number of viable seed and percent viable seed (table 3).